A study by researchers from the National University of Singapore (NUS) and the University of São Paulo revealed that a beltway constructed to divert heavy-duty diesel vehicles traffic in the Brazilian city of São Paulo improved air quality and public health in the city. The study was published in the Journal of the European Economic Association . The positive health outcomes of the intervention could guide the formulation of similar transport polices in other cities, where humans and diesel vehicles reside and transit in close proximity. In 2010, São Paulo constructed a beltway along sparsely populated areas that are 25 kilometers away from the city center. The original intent of building the beltway was to enable heavy-duty vehicles to bypass the densely populated neighborhoods, and thereby ease traffic congestion in the inner-city roads. While the intervention did immedi...